I honestly can't even remember the Gematsu leak, but I'm always skeptical of these things, so it's likely.
That said, Vergeben is dubunked by the mere fact that he got the DBFZ roster totally wrong, and the DLC too, and he incorrectly said Cervantes wouldn't be in SCVI.
People like to say:
"but he correctly guessed we'd get a new SamSho, and that the trailer would feature Nakoruru"
You mean, he predicted SNK's 2nd most popular franchise would make a return after the flop that was the new KoF, in an era where fighting games are seeing a Renaissance, and the trailer would feature THE most iconic character in the SamSho franchise, so iconic she's made cameoe outside of it? Predictions btw, that were heavily speculated for months before he ever made his claim?
I don't buy into Verg because he's wrong too often to be a credible source, and most of his accurate predictions are very safe, and had been speculated upon well before his claims. On Smash alone, the fact that neither Incineroar nor a Minecraft character aren't in are reason enough to be highly skeptical of all his claims.
I can make lucky guesses too.